Sulphuric acid treatment of dewaxed petroleum stocks at low temperature



Dec. 13, 1938. E, J. MARTIN 2,140,161 SULPHURICl ACID TREATMENT 0F DEWAXED PETROLEUM STOCKS AIT LOW TEMPERATURE Filed Nov. 14, 1954 Wax-bean@ fan/2 fdr/ Affi/hy 2 5 ATTORNEYS Patented Dec. 13, 1938 UNITED STATES PATENT OFFICE SULPHURIC ACID TREATMENT OF DE- WAXED PETROLEUM STOCKS AT TENIPERATURE LOW Application November 14, 1934, Serial No. 752,027

9 Claims.

This invention relates to improvements in the manufacture of lubricating oils from wax bearing petroleum stocks. In referring to lubricating oils, reference is intended to petroleum oils,

5- having a viscosity upwards of 70 seconds at 100 F. Saybolt Universal More particularly, the invention provides an operation comprising the sulphuric acid treatment of deWaXed petroleum stocks at low tem- 10l perature. The invention makes possible the production, with good economy, of lubricating oils of good color and of low Conradson carbon content, the development of good acid efficiencies, and improvement of the product, particularly with re- 151 speot to color, with minimum losses during the refining operation.

According to the present invention, the petroleum stock is deWaXed and the dewaxed oil is treated with sulphuric acid While maintaining a temperature not substantially exceeding F. during acid addition and acid contact and during the subsequent separation of sludge formed as a consequence of the acid treatment. The acid treatment of the dewaxed oil, and the subsequent sludge separation, are with advantage carried out at temperatures as low as 10 F. or lower. A temperature not substantially exceeding 0 F., or better not substantially exceeding 10 F., is with advantage maintained during wax separa` tion as well as acid addition, acid contact and sludge separation. l1. previously dewaxed oil, however, may be cooled to the temperature to be maintained during acid treatment and sludge separation immediately prior to acid addition.

The acid treatment and sludge separation, in the combined operation of the invention, are with advantage carried out in the presence of an admixed diluent, a naphtha or a liquefied normally gaseous hydrocarbon or mixture of hydrocarbons such as the so-called liquid propane fraction comprising about 70% of propane, for example. Naphthas boiling Within a range approximating 200-400 F., naphthas having a boiling range of 200-300 F. or of 300-400 F. for example, are 'i useful in carrying out the invention'. Such diluents are with advantage added to the oil prior to the dewaXing operation. While the manner in which the dewaxing operation is carried out is not essential to the invention, the dewaxing operation of the combined operation of the invention is with advantage carried out in the presence of an admixed diluent as in conventional practice, The diluted dewaxed oil may then be subjected directly tothe low temperature acid treatment. The same or a different diluent may,

however, be admixed with the oil following the dewaXing operation and` before the acid treatment In one advantageous embodiment of the invention, the wax bearing stockis diluted With a liquid propane or its equivalent, this stock mixture is chilled by vaporization of a part of the admixed liquid propane, the wax thus precipitated is separated from the remaining oildiluent mixture, and the dewaxed diluted oil is then subjected to acid treatment followed by sludge separation, the low temperature maintained during acid treatment and sludge separation in accordance with the invention being established by the chilling iirst mentioned.

When the deWaXed and acid treated oil, after sludge separation, is to be treated with an absorbent earth as a nishing operation, the absorbent earth is with advantage added to the diluent oil immediately after sludge separation and the oil-earth-diluent mixture is with advantage heated but once both to activate the absorbent earth and to vaporize the remaining diluent from the lubricating oil product. Not only is an operating economy thus effected, but also any danger of impairing the quality of the product by heating the acid treated oil to eliect separation of the diluent except in contact with the absorbent earth is thus avoided. Reference to addition of the absorbent earth to the diluted acid treated oil immediately after sludge separation is intended to refer toaddition of the absorbent earth tol the acid treated oil before the acid treated oil has attained any temperature at which degradation due to the remaining acid or acid reaction products is involved. The absorbent earth is with advantage added to the oil before its ltemperature has risen much above that at which sludge separation is effected.

It has hitherto been proposed to subject unde- WaXed petroleum stocks to acid treatment at low temperature. It has also been proposed to subject undewaxed petroleum stocks to acid treatment at high temperature followed by chilling to a low temperature at which sludge and wax are together to be separated from the oil- The presence of the Wax during acid treatment impairs the acid efliciency, Also, the separation of Wax and sludge together from the oil is subject to inherent diiculties in that wax crystals present interfere with the formation and separation of the sludge and the sludge present interferes with the separation of the Wax. This invention is distinguished from such proposals in that, according to this invention, the stock subjected to at I.

- a temperature of 0 F. or 10 F. or 20 F. for

acid treatment has previously been dewaxed. The acid treatment as well as the sludge separation, moreover, are, according to this invention, eected at low temperature.

The invention Will be further described in connection with the accompanying drawing which, as a flow diagram, illustrates a specic embodiment of the combined operation of the invention.

Referring to the drawing: The Wax bearing-r stock to be treated is mixed withY an appropriate diluent, naphtha or liquid propane, as indicated The diluted Wax bearing stock is chilled to example as indicated at 2. Precipitated Wax is separated from the chilled diluted' stock as indicatedat 3. 'I'he cold diluted deWaXed stock is subjected to treatment with concentrated sulphuric acid as indicated at 4 and the resulting sludge is separated as indicated at 5. Anabsorbent earth is added vto the co-ld diluted dewaxed and treated stock as indicated at 6. This stock-earthdiluent mixture is heated as indicated at 1, the vaporized diluent is separated as, indicated at 8 and condensed or liquefied to be re-used as indicated at I, and the spent earth is separated from the finished lubricating oil as. indicated at 9. The low temperature established by the chilling indicated at 2 is, with advantage, maintained wi-th a minimum increase through the Wax separation, the acid treatment and the sludge separation indicated at 3, 4 and 5. 'I'he acid treatment and sludge separation indicated at 4 and 5 may, however, be effected at temperature somewhat above the temperature of wax separation.

The invention will be. further illustrated by the following examples of specic operations embodying the invention:

A Pennsylvania long residuum having a gravity of 26.0 B., a viscosity of 131 seconds at 210 F. Saybolt Universal, a pour test of 55 F. and a Conradson carbon content of 2.154% was dewaxed in the conventional manner to produce a dewaxed oil having a gravity of 24.3 B., a viscosity of 150 seconds at 210 F. Saybolt Universal, a pour test of 10 F., a Conradson carbon content of 2.645%. One portion of this deWaXed oil Was diluted with 1.5 times its own volume of naphtha. This oil diluent mixture was treated with 40 pounds per barrel of 66 B. sulphuric acid and the resulting sludge separated While maintaining a temperature during acid addition, acid contact and sludge separation of 10 F. The acid treated oil-diluent mixturer Was heated to a temperaturev of 500 in admixture With 20% by Weight of added Olmstead earth. The sludge loss on the deWaxed oil amounted to 13.6%. After separation of the diluent and spent earth, a lubricating oil product having a gravity of 25.5 a viscosity of seconds at 210 F. Saybolt Universal, a pour test ofV 8 F., a Conradson carbon content of 1.218% and of good color Was obtained. Another portion of this dewaxed oil was diluted with three times its own volume of liquid propane. This oil diluent mixture was treated with 40 pounds per barrel of` 66 B. sulphuric acid and the resulting sludge separated while maintaining a temperature during acid addition, acid contact and sludge separation of 10 F. Thel acid treated oil-diluent mixture was heated to av temperature of 500 F. in admixture With 20% by weight of added Olmstead earth. The sludge loss on the dewaxed oil amounted to 13.6%. After separation of the diluent and spent earth, alubricating oil product having a gravity of 25.8 B., a

viscosity of 123.3 seconds at 210 F. Saybolt Universal, a pour test of 10 F., a Conradson carbon content of 1.132% and of good color was obtained.

With respect to economy, it is to be noted that although, in carrying out the invention, Wax separation and sludge separation are separately effected, the burden oi refrigeration is not required to be increased since the intervening acid treatment is also eiected at a loW temperature.

I claim:

1. In the manufacture of lubricating oils from Wax-bearing petroleum stocks, the improvement Which comprises dewaxingthe oil, and thereafter treating the dewaxed oil with concentrated sulphuric acid and separating the resulting sludge While maintaining a temperature not substantially exceeding 0 F. during acid addition, acid contact and sludge separation.

2. In the manufacture of lubricating oils from wax-bearing petroleum stocks, the improvement which comprises dewaxing the oil, thereafter treating the dewaxed oil withr concentrated sulphuric acid and separating the resulting sludge While maintaining a temperature not substantially exceeding 0 F. during Wax separation, acid addition, acid contact and sludge separation.

3. In the manufacture of lubricating oils from Wax-bearing petroleum stocks, the irriprovement` which comprises diluting the oil, dewaxing the diluted oil, and thereafter treating the devvaxed diluted oil with concentrated sulphuric acid and separating the resulting sludge While maintaining a temperature not substantially exceeding; 0 F. during acid addition, acid contact and. sludge separation.

4. In the manufacture of lubricating oils from Wax-bearing petroleum stocks, the improvement which comprises devvaxing the oil, and thereafter treating the dewaxed oil inl admixture with a diluent With concentrated sulphuric acid and separating the resulting sludge While maintaining a temperature not substantially exceedingY 0 F. during acid addition, acid contact and-sludge. separation.

5. In the manufacture of lubricating oils from Wax-bearing petroleum stocks, the improvement which comprises dewaxing the oil, and there-I after treating the devvaxedV oil with concentrated sulphuric acid and separating the resulting sludge While maintaining a temperature not substantially exceeding 0 F. during acid addition, acid contact and sludge separation, adding an absorbent earth to the acid treatedoil immediately' after sludge separation, heating the oil-earth mixture and thereafter separatingV the spent earth from the oil.

6. In the manufacture of lubricating oils fromI Wax-.bearingy petroleum stocks, the improvement which comprises dewaxing the oil, and thereafter treating the dewaxed oil in admixture with a diluent With concentrated sulphuric acid andseparating the resulting sludge while maintaining a temperature not substantially exceeding 0 F. during acid addition, acid contact and sludge separation, adding an absorbent earth to the diluted acid treated oil immediately after sludge separation, heating the oil-earth-diluent mixture and separating the diluent and the spent earth from the oil.

'7. In the manufacture of lubricating oils from Wax-bearing petroleumv stocks, the improvement Which comprises dewaxing the oil, and thereafter treating the dewaxed oil with concentrated sulphuric acid and separating the resulting sludge lil While maintaining a temperature notV substan- 15.

tially exceeding -10 F. during acid addition, acid contact and sludge separation.

8. In the manufacture of lubricating oils from Wax-bearing petroleum stocks, the improvement which comprises dewam'ng the oil, treating the dewaxed oil with concentrated sulphuric acid and separating the resulting sludge while maintaining a temperature not substantially exceeding -10 F. during wax separation, acid addi- 10 tion, acid contact and sludge separation.

9. In the manufacture of lubricating oils from Wax-bearing petroleum stocks, the improvement which comprises dewaxing the oil, and thereafter treating the dewaxed oil in adrnixture With a diluent with concentrated suiphuric acid and separating the resulting sludge While maintaining a temperature not substantially exceeding 10 F. during acid addition, acid contact and sludge separation.

EDWARD JOHN MARTIN.

, CERTIFICATE CF CORRECTION. Patent No. 2,1LL0,161. Deqember 15, 1958.

EDWARD JOHN MARTIN,

It is hereby Certified that error appearsfn the printed specification l of the above numbered patent'requiring correction as follows: P age 5, first column, line 5, clam, before "treating" insert the word thereafter; and that the said Letters` Patent should be read with this correction-therein that the 'same may lconform Ato the record of the cese in the. Paten-t Office.

signed and sealed this authdvay of January, A. D'. 1959.

Henry van Arsdale (Seal) Acting Commissioner of Patents 

